View attachment 65825
So I finally was able to come to a conclusion as to what took place. Before I add it here, I do want to say that I used BudWalker's programs to help. His DatCon (short for DAT Converter) program converted the file to a readable format. I then used his CsvView (short for CSV Viewer) is what you get to see in action in the image above. I completely appreciate the time and effort he put into both setups. The help save a lot of people from having to depend on limited resources.
I have diagnosed close to 200ish flights now and every now and then you come across one a little different then the others. On this flight here I spent a lot of time looking for the more common issues that pop up. I actually have 4hrs in this one here, but, if one like it shows up again in the future I will have it tackled in 15-20mins.
I was lucky enough to diagnose a litchi flight a week ago which helped with reaching my final conclusion on this flight. I want to point out some things in the image to help those looking at it for the 1st time to have a little idea what things are as a reference.
1st)To begin with, the horizontal line seen in red represents two separate values. The -0 - 920 is the number of seconds. In this case 920 seconds equals about a 15.30 flight.
2nd)The second part to the red line represents the Forward & Back Stick on the R/C. The higher the line goes up the graph in this instance shows how much the Stick is being pushed upward on the R/C.
3rd)Shows the blue line which is battery voltage throughout the flight.
4th & 5th)The last two lines which are purple and gold in this case show the Front Motor Speed throughout the flight.
I only showed the two front motors because it can get very confusing when you have a lot of line info being displayed on the graph. When looking at the data for these two lines, you only need to notice that in the boxes on the bottom of the graph describe them as being Motor Speed which is rpms. Here they show they're consistent thru the 1st 3/4ths until near the end of the flight the behavior changes.
Since the last A/C firmware update which was version 1.9.6, doesn't seem to communicate well with the litchi app. I'm pretty sure what has happened with this flight is, in certain battery situations when the voltage drops the aircraft is now programmed to restrict the voltage from the battery and display a message on the screen. In this case the aircraft was on a mission and in F-mode on the R/C. When the remaining battery voltage reached a set limit with in the firmware, the aircraft removed voltage which also consists of reducing speed. The litchi app didn't like it since it itself is programmed to run the aircraft at a set speed by the operator when the mission was setup. The result in this case was the two setups(a/c firmware vs. litchi app) were working against each other causing the aircraft to not fly as it normally would.
Btw, you can see in the graph when the craziness began to take place. And if you look at the blue voltage line you will see that it played havoc on the battery itself. Had that low point went a little further, this aircraft may have shut down while in flight. At any point should any of the 4 battery cell's reach 3.0 volts...let's just hope this months insurance payment was made.
Also most of you aren't aware of this, but dji programmed the battery firmware to display a false reading. This was done so the battery functions on a smaller storage reserve. Changes applied throughout the battery reserve were when the remaining amount in a cell displays say 3.0 volts, the battery actually has 3.5 volts. This is why a year ago when P3's were dropping from the sky, dji had made the change in the battery firmware but did not realize they also needed to add the change to aircrafts firmware to match it.
Bonehead83, you might ask BudWalker to have a look at the file also. He is really good with these programs since he created them and likely can find a more technical diagnoses, if you want another one that is. Either way I hope this helps you.